发布日期：2009-03-25
更新日期：2009-03-30

受影响系统：

Cisco IOS 12.4
Cisco IOS 12.3  
Cisco IOS 12.2
Cisco IOS 12.1
Cisco IOS 12.0

描述：

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BUGTRAQ  ID: 34243
CVE(CAN) ID: CVE-2009-0636

Cisco IOS是思科网络设备所使用的互联网操作系统。

如果Cisco IOS设备配置的VoIP功能中处理SIP消息，远程攻击者就可以通过发送畸形SIP报文导致设备重载。

<*来源：Cisco安全公告
  
  链接：http://secunia.com/advisories/34438/
        http://www.cisco.com/warp/public/707/cisco-sa-20090325-sip.shtml
*>

建议：

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临时解决方法：

* 禁用SIP监听端口

     sip-ua
     no transport udp
     no transport tcp

* 应用以下控制面整型（CoPP）
  
    !-- The 192.168.1.0/24 network and the 172.16.1.1 host are trusted.
    !-- Everything else is not trusted. The following access list is used
    !-- to determine what traffic needs to be dropped by a control plane
    !-- policy (the CoPP feature.) If the access list matches (permit)
    !-- then traffic will be dropped and if the access list does not
    !-- match (deny) then traffic will be processed by the router.

    access-list 100 deny udp 192.168.1.0 0.0.0.255 any eq 5060
    access-list 100 deny tcp 192.168.1.0 0.0.0.255 any eq 5060
    access-list 100 deny tcp 192.168.1.0 0.0.0.255 any eq 5061
    access-list 100 deny udp host 172.16.1.1 any eq 5060
    access-list 100 deny tcp host 172.16.1.1 any eq 5060
    access-list 100 deny tcp host 172.16.1.1 any eq 5061
    access-list 100 permit udp any any eq 5060
    access-list 100 permit tcp any any eq 5060
    access-list 100 permit tcp any any eq 5061

    !-- Permit (Police or Drop)/Deny (Allow) all other Layer3 and Layer4
    !-- traffic in accordance with existing security policies and
    !-- configurations for traffic that is authorized to be sent
    !-- to infrastructure devices.
    !-- Create a Class-Map for traffic to be policed by
    !-- the CoPP feature.

    class-map match-all drop-sip-class
      match access-group 100

    !-- Create a Policy-Map that will be applied to the
    !-- Control-Plane of the device.

    policy-map drop-sip-traffic
     class drop-sip-class
      drop

    !-- Apply the Policy-Map to the Control-Plane of the
    !-- device.

    control-plane
     service-policy input drop-sip-traffic

厂商补丁：

Cisco
-----
Cisco已经为此发布了一个安全公告（cisco-sa-20090325-sip）以及相应补丁:
cisco-sa-20090325-sip：Cisco IOS Software Session Initiation Protocol Denial of Service Vulnerability
链接：http://www.cisco.com/warp/public/707/cisco-sa-20090325-sip.shtml

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